PROJECT SUMMARY Understanding the role of dietary intake in nutrition, health, and disease is the underlying goal of much of modern nutrition research. Fundamental to the core of nutritional science in humans is the assessment and monitoring of dietary intake, of which the current methods are the ultimate bottleneck towards scientific progress in the field. Methods that contribute to dietary assessment that measure intake in real time, improve reliability and validity, and deal with the inherent variability of nutrients in foods will fundamentally change how dietary intake is assessed and monitored, altering the way nutritional science and clinical care related dietary intake are carried out. However, the devices and methods that will address these fundamental roadblocks do not exist- no automated method of tracking when, how, or what people are consuming, much less quantitative techniques to measure the actual nutrients people are consuming within their diet over time are ready for primetime. Such techniques would not only give scientists and clinicians a powerful tool to track dietary intake, but could have numerous applications in population health and clinical care. There have been numerous attempts with limited utility made to address this issue. Currently, existing devices to monitor the mouth in-situ for dietary intake have been limited. Examples have including electrochemical sensors that are limited in the scope of their detection (demonstrated devices can only detect urea), possess low lifetime, have questionable biocompatibility, and are difficult to calibrate in complex fluidic environments. One area that could address this problem is RFid (dielectric) tattoos, an elegant concept with demonstrable utility fit on bovine teeth, but limited bio-sensitivity and loss of signal in high salinity environments. Recently, we have developed a novel format of RFid sensor, whose unique bio-sensitivity is driven via bio-amplification in the form of a mechanically- swelling, hygroscopic interlayer sandwiched between split-ring antennas (that we term a bio-interlayer-RFid). This concept infuses some of the sensitivity of electrochemical sensors into the long-term, bio-compatible format of dielectric sensors. We have successfully demonstrated the viability of these sensors in-situ within human mouths, and preliminarily discriminated nutrients such as water, ethanol / fat, salts, glucose (in addition to the drying of mouth). This discrimination was extracted from real-world bio-fluids such as drinking water, mouthwash, soup, and apple juice at reasonable time frames (30 seconds ? 2 minutes). This proposal will utilize these sensors to develop a first-in-class device to continuously measure nutrients directly from the foods we eat. This will be accomplished via aims that seek to: (1) Further develop and improve bio-interlayer- RFid sensitivity and responsive time, (2) Development of a wireless and wearable RF-circuit to read-out data from interlayer-RFids, and (3) In-vitro characterization and validation of our wearable device with a dynamic face model.